Multi-compartment bag with breakable walls

ABSTRACT

The invention relates to a multi-compartment bag which provides for the separation of two substances until their desired intermixing. A specific application of this multi-compartment bag is for hot or cold chemical packs. The substances in the multi-compartment bag are separated by two breakable walls and a third compartment which together act as a barrier to migration of one substance into the second substance, which would reduce the shelf life and efficiency of the hot or cold chemical pack. The present invention&#39;s use of two breakable walls and a compartment, empty or containing an inert substance, separating two reactive substances, provides a longer shelf life, a high efficiency, more reliability and improved ease of operation.

RELATED APPLICATIONS

This application is related by subject matter to copending, co-ownedU.S. application Ser. No. 08/403,295, filed Mar. 14, 1995, "A ReusableHot or Cold Chemical Therapy Pack", and copending application Ser. No.08/954,844.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a multi-compartment bag for mixing a firstsubstance with a second substance. More particularly, thismulti-compartment bag utilizes first and second breakable walls with acompartment there-in-between which acts as a barrier to pre-activationintermixing of the first substance and the second substance. A desireduse of the multi-compartment bag is hot or cold chemical packs.

BACKGROUND OF THE INVENTION

Multi-compartment bags are known for use in a variety of applications,including mixing two reactants to produce an endothermic or exothermicreaction for a number of uses, including therapy for muscular injury orcirculatory problems or heating or cooling food. Multi-compartment bagshave also been used for applications such as mixing resins with aninitiator prior to use of the resin.

Cold packs have been used to treat injuries such as sprained muscles orinjured joints. Generally, the cold packs are used to slow blood flow,and reduce swelling, pain and further damage.

Heat packs have been used to warm muscles or reduce cramping. Generally,heat packs increase blood flow.

Hot and cold packs are generally of two types: those that requireexternal heating or cooling, and "chemical packs" which mix two or morereactants to cause an endothermic or exothermic reaction. It is desiredthat chemical packs have a long shelf life and be activated only upon anintentional activation, and not in shipping or handling.

The chemical packs generally come in two varieties: the bag-in-bag typeor the side-by-side type. The bag-in-bag type pack has two separatebags, with a smaller bag containing one of the reactants included withinthe larger bag which contains the other reactant. Bag-in-bag chemicalpacks suffer from the significant disadvantage that there is a largesurface area, represented by the exterior surface of the smaller bag,between the first reactant and the second reactant. Here, if a reactantis a liquid or gas, it will migrate through the plastic material of thesmaller bag and into the second reactant causing a pre-activationintermixing of the reactants which results in a short shelf life and alower efficiency upon intentional activation. This migration through thesmaller bag can be slowed by using a thicker plastic material for thesmaller bag; however, when a thicker smaller bag is utilized, it becomesmore difficult to activate the pack when activation is desired. Also,with the bag-in-bag design, it is sometimes difficult to rupture thesmaller bag. A number of prior art devices have utilized a rigid spiketo facilitate rupturing the smaller bag. This presents significantshortcomings in that the rigid spike may puncture the larger bag in useor in shipping and handling causing external leaking.

The side-by-side bags utilize a breakable seal between two compartmentslocated side-by-side, each compartment containing one of the reactants.These side-by-side packs attempt to utilize a strong seal around theperimeter of the bag and a weak seal to separate the two compartments.This is very difficult to do on a consistent basis and with knownmanufacturing techniques and leads to a situation where a force,intended to mix the two reactants, breaks an exterior seal causing aleak of the reactants onto the potential user.

Various mechanical devices have been used to prevent the mixing of twocomponents in multi-compartment bags. These mechanical devices may beeither externally mounted or internal to the bag, such as, for example,a groove provided on the inner side of one sheet which connects with arib on the inner side of the opposite sheet, the groove and rib beingengaged to seal and prevent intermixing of the two reactants, with therib and groove being separated to permit intermixing. These mechanicalseals suffer from significant shortcomings. First, mechanical sealsinvariably leak and are not as reliable as other sealing methods. Also,during shipping and handling, mechanical seals have a higher rate ofaccidental activation, resulting in unusable product.

U.S. Pat. No. 4,427,010 to Marx utilizes a side-by-side bag wherein abreakable wall is used instead of a breakable seal. This overcomes theproblem of manufacturing a seal which ruptures at the desired force;however, this bag still has the significant shortcoming of a largesurface area between the first and second reactants which, uponmigration of one reactant through the plastic sheet into the otherreactant, reduces the shelf life and efficiency of the product.

Another shortcoming of the prior art chemical packs is that they do notprovide any means to fasten the chemical pack to a user wishing to applythe chemical pack in a therapeutic fashion to a particular part of hisbody. Prior art ice packs, i.e., packs wherein ice is added for eachuse, have employed ties and other fastening means. However, these icepack fastening means suffer from several shortcomings. First, if notused carefully or if overstressed, these fastening means may cause therupturing of a seam or tearing of a pack resulting in external leakingof ice and water. While this is an undesired result with ice packs, itpresents a much more serious concern with chemical packs, where therupturing of a seal or tearing of a pack could result in release ofchemicals onto the user. Also, depending upon the ice pack chosen, theties may be difficult to use or expensive to manufacture.

There exists a need for a multi-compartment bag for mixing twosubstances, and more particularly, for a hot or cold chemical pack formixing two substances, which has a long shelf life and wherein the forcerequired to mix the two substances is predictable, such that thesubstances will be mixed upon an intended activation by the user, andnot in normal handling and shipping. There further exists a need for achemical pack with suitable ties for fastening the chemical pack to auser.

SUMMARY OF THE INVENTION

The invention relates to a multi-compartment bag for mixing a firstsubstance with a second substance where the two substances are separatedby a compartment which is empty or which holds an inert substance. Thefirst compartment holding the first substance is separated from thethird compartment, which is empty or which holds an inert substance, bya first breakable wall, and the second compartment holding the secondsubstance is separated from the third compartment by a second breakablewall. The two breakable walls and the third compartment act as aneffective barrier for migration of one substance into the othersubstance which would lead to a short shelf life or a low efficiencyreaction upon intentional activation.

It is an object of this invention to provide a hot or cold chemical packwhich has a long shelf life.

It is further an object of this invention to provide a hot or coldchemical pack which upon intentional activation is easily activated, butwhich is able to withstand shipping and handling without unintentionalactivation.

It is still further an object of this invention to provide a hot or coldchemical pack which has suitable ties to enhance its usefulness.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1 and 1A are side views of a multi-compartment bag with breakablewalls designed for holding two substances.

FIG. 2 is a top view of the FIG. 1 device.

FIGS. 3 and 3A are side views of multi-use chemical packs which providefor two uses.

FIG. 4 is a top view of a multi-compartment bag having ties.

FIG. 5 is an end view of the multi-compartment bag of FIG. 4.

FIGS. 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10 show the method ofmanufacturing the multi-compartment bag of FIGS. 1 and 2.

FIGS. 11-18 show side views of alternate embodiments ofmulti-compartment bags.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The preferred embodiments of the present invention and its advantagesare best understood by reference to FIGS. 1-18 of the drawings, likenumerals being used for like and corresponding parts of the variousdrawings.

FIG. 1 shows a multi-compartment bag 20 having a first compartment 11and second compartment 12. The compartments 11 and 12 are separated by afirst breakable wall 5A and a second breakable wall 5B. Breakable walls5A and 5B serve as part of the perimeter of a third compartment 13 whichseparates the first compartment 11 and the second compartment 12 andwhich acts as a barrier to prevent migration of a substance contained ineither compartment 11 or 12 into the other compartment 11 or 12.

FIGS. 1 and 2 show the overall construction of a three-compartment bagwith two breakable walls 5A, 5B, which provides for the mixing of twosubstances. A first substance is stored in compartment 11 and a secondsubstance is stored in compartment 12. This multi-compartment bag isconstructed of a top sheet 3 and a bottom sheet 4 which is sealed on itsends via seals 1 and 2, and which is sealed about its perimeter by seals1, 2, 9, and 10. This forms an internal compartment which is thecombination of compartments 11, 12 and 13. Within this internalcompartment is located breakable sheet 5 which separates the overallinternal compartment into the three compartments 11, 12, and 13.Breakable sheet 5 is sealed to bottom sheet 4 via seal 6 which extendsacross the width of bottom sheet 4. The middle section of breakablesheet 5 is sealed to top sheet 3 at seal 7. Breakable sheet 5 is alsosealed to the bottom sheet 4 at seal 8. Seals 7 and 8 extend across thewidth of the top sheet 3 and bottom sheet 4, respectively.

Thus, in the embodiment of FIGS. 1 and 2, there are formed threecompartments 11, 12, 13. The first compartment 11 is formed by aperimeter consisting of top sheet 3, bottom sheet 4, and first breakablewall 5A, which is a section of breakable sheet 5. The second compartment12 is formed by a perimeter including top sheet 3, bottom sheet 4 andsecond breakable wall 5B, which is a second section of breakable sheet5. The third compartment 13 is formed by a perimeter consisting ofbottom sheet 4, breakable wall 5A, seal 7, and breakable wall 5B.

For application as a hot or cold chemical pack, it is intended that thefirst compartment 11 hold the first substance and the second compartment12 hold the second substance which, upon intermixing, causes the desiredendothermic or exothermic reaction.

For an endothermic reaction, it is known in the art that a reaction ofwater and ammonium nitrate causes an endothermic reaction and providesfor a cold chemical pack. Here, water would be held in one compartment,for illustrative purposes the first compartment 11, and sphericallyshaped beads (not shown) of ammonium nitrate, a solid salt, known in theart as "prills," would be located in a second compartment, forillustrative purposes the second compartment 12. When a user desires toactivate the chemical pack 20 to achieve the desired cold pack, the userwould exert a force, such as by squeezing, first compartment 11. Thisforce, hydraulically transmitted by the liquid water in compartment 11,presses against the first breakable wall 5A and causes it to rupture.The same force then is transferred to breakable wall 5B where itruptures breakable wall 5B. After both breakable walls 5A and 5B areruptured, the water intermixes with the ammonium nitrate prills causingan endothermic reaction, providing the desired cold pack.

It has been found that due to the forces exerted upon a chemical pack 20of the FIGS. 1 and 2 embodiment that the first breakable wall 5Aruptures at line 14 and the second breakable wall 5B ruptures at line15.

It is known in the hot chemical pack art that the crystallization ofsuper-cooled sodium acetate liquid releases heat which is suitable for ahot chemical pack application. It is known that super-cooled sodiumacetate liquid is stable, but upon "initiation", begins to crystallizeand releases heat. One such way of initiating this crystallization isthe intermixing of the super-cooled sodium acetate liquid with sodiumacetate crystals (solid). Thus, in use as a hot pack, the super-cooledsodium acetate liquid would be held in a first compartment, e.g.,compartment 11, and sodium acetate crystals would be contained in asecond compartment, e.g., compartment 12.

It is also known in the hot chemical pack art that the combination ofsodium thiosulfate, a solid salt, and glycerine produces an exothermicreaction.

In the applications noted above, the chemical pack 20 would include botha liquid and a solid. In this situation, it is preferable to exert aforce upon the compartment containing the liquid, here compartment 11.This force is hydraulically transmitted to the first breakable wall 5Awhere, when a sufficient force is exerted, ruptures the first breakablewall 5A. The liquid and hydraulic force proceeds to the second breakablewall 5B, where, when a sufficient force is exerted, ruptures wall 5B,causing an intermixing of the liquid and the solid. It is generally notpreferred that a force be exerted to a compartment containing a solid,as a solid will not hydraulically transmit the force to the breakablewall 5A, 5B. However, if the compartment containing the solid alsocontains air or another gas, this gas can be used to hydraulicallytransmit a force and rupture a breakable wall 5A, 5B.

There are many known endothermic and exothermic reactions which utilizetwo liquids. In this situation, force could be applied to eithercompartment 11 or 12 to rupture the breakable walls 5A, 5B.

It is known that a gas or liquid substance migrates across a singleplastic sheet at a rate dependent upon the type of plastic and thethickness of the sheet. Prior art devices have attempted to minimizethis migration by providing thicker plastic sheets. However, thickerplastic sheets are harder to intentionally rupture to activate the pack.

Since significant migration occurs over time across a single plasticsheet, any design which allows two reactive substances to be placed inproximity should be avoided, or the material of the sheet should be of athicker, less permeable material.

As mentioned above, the prior art devices suffer from two mainshortcomings. First, where a single plastic sheet separates the tworeactants, migration of one of the reactants across this sheet causes apre-activation intermixing of the two reactants which slowly over timecauses a significant portion of the reactants to be reacted prior to thedesired activation of the device, resulting in a short shelf life andlow efficiency upon activation. The present invention overcomes thisshortcoming by providing two breakable walls 5A, 5B, and a thirdcompartment 13 interposed between the two compartments 11 and 12containing the substances to be mixed to provide the endothermic orexothermic reaction.

With the present invention, if a substance migrates through a walltowards the second substance, this substance will enter the thirdcompartment 13. Since migration across a permeable membrane is directlyrelated to the difference in concentration across that permeablemembrane, there must first be a significant buildup or concentration ofthe substance in compartment 13 before it will migrate through thesecond breakable wall 5B into the second compartment 12. Thissignificantly increases shelf life and reaction efficiency uponactivation over the prior art devices.

Second, with the side-by-side multi-compartment bags of the prior artwhich utilized rupturable seals, it is very difficult to provide a sealwhich would rupture upon a desired predetermined force. The breakablewalls 5A, 5B of the present invention are a much more reliable way ofproviding a rupturable barrier to provide intermixing of the twosubstances. The thickness of breakable sheet 5 can be adjusted so thatbreakable walls 5A and 5B would rupture upon a desired predeterminedforce.

The method of manufacturing the multi-compartment bags 20 of the FIGS. 1and 2 embodiment is shown in FIGS. 6-10. While this manufacturingtechnique is particularly applicable to the FIGS. 1 and 2 embodiment, itis also applicable to the alternate embodiments (FIGS. 11-18), discussedbelow, and the multi-use chemical packs (FIGS. 3 and 3A), discussedbelow. Also, while this method of manufacturing is particularlyapplicable for multi-compartment bags which have two breakable walls anda third compartment separating the two substances to be mixed, thismanufacturing technique may also be used for a multi-compartment bagwith just one breakable wall between the two compartments which may beused in situations where the substances do not migrate or have a lowmigration rate across the breakable wall. FIGS. 11 and 16 representmulti-compartment bags having one breakable wall 5 which separates thetwo substances to be mixed and which are manufactured by the method ofthe present invention.

In the discussion as follows, sheets 3, 4 and 5 are generally on rollswhich may be the width of a single finished bag or several finishedbags. Preferably, sheets 3, 4 and 5 are initially on a roll with alength much longer than an individual bag to provide for continuousmanufacturing.

FIGS. 6A and 6B shows the starting point of the manufacturing technique,i.e., providing a first sheet (here sheet 3) for a first exterior wallof the first compartment 11 and the second compartment 12. Sheet 3 hasan interior surface 3A to which the breakable sheet (sheet 5) is sealed(seal 7). Preferably, the seals are heat seals which may be made by heatrollers (continuous operation) or by heat bars (stop and startoperation) as is known to those of skill in the art. As shown in FIGS.7A and 7B, preferably, sheet 5 is sealed to sheet 3 along a centersection of sheet 5, such that sheet 5 has two loose sides which may besealed to sheet 4 as discussed below. However, for the embodiment whereonly one breakable wall is provided (FIG. 11), sheet 5 is sealed tointerior surface 3A at a side of sheet 5.

FIGS. 8A and 8B show the loose sides of sheet 5 being sealed to sheet 4along its interior surface 4A, forming seals 6 and 8.

As shown in FIGS. 9A and 9B, at a lower section, the sides of sheets 3and 4 are brought together and sealed together via seals 1 and 2.Preferably, seals 1 and 2 are greater than about one bag length but lessthan about 3 bag lengths so as to facilitate the addition of the firstsubstance 63 and the second substance 64 as discussed below. Also, seal10 is made so as to form the first compartment 11 and the secondcompartment 12, both with open ends. Preferably, this and the previousstep also form the third compartment 13, also having an open end.

To the open-ended compartments, via hoses or other conduits 61 and 62,the first substance 63 and second substance 64 are added to the openended first compartment 11 and second compartment 12. If desired, aninert substance may be added to the third compartment 13 at this stage,otherwise the third compartment is left essentially empty or may containsome air. The open end, preferably the top of the open-endedcompartments 11, 12, 13 is sealed with a double width seal which formsseal 9 of a bag being completed and seal 10 of a bag prior to its beingfilled with the first and second substances 63 and 64. Then, the doublewidth seal is cut, forming the completed multi-compartment bag 20.

With this method of manufacturing, seals 9 and 10 are made after andsuperimposed upon seals 6, 7, and 8. This is the preferred method ofmanufacturing as this provides a stronger seal about the perimeter ofthe bag 20 to prevent external leaking while also ensuring that seals 6,7 and 8 extend the whole width of an individual bag 20 such that thereis no internal leaking from one compartment to another.

This method of manufacturing multi-compartment bags 20 may also be usedto manufacture the multi-use-packs 30, discussed below, with additionalsteps apparent to one of skill in the art in light of the disclosureabove.

FIGS. 11-18 show alternate embodiments of the multi-compartment bag 20which may be manufactured by this method.

FIG. 11 shows a single breakable wall embodiment which may be used whenthe substances do not migrate across the breakable wall 5, there is aslow rate of migration, or the product does not need a long shelf life.

FIG. 12 shows an embodiment similar to the FIGS. 1 and 2 embodiment;however, a single seal 6A is used to seal both breakable walls 5A, 5B tothe interior surface 4A of sheet 4.

FIG. 13 shows an embodiment where two seals 7A, 7B are used in place ofseal 7 to seal sheet 5 to the interior surface 3A of sheet 3.

FIG. 14 shows an embodiment where three breakable walls and twocompartments are utilized to separate the compartments holding the firstand second substances. This may be used to provide additional shelf lifeor to further reduce the number of chemical packs which areunintentionally activated during shipping and handling.

FIG. 15 shows an embodiment similar to FIGS. 1 and 2 where sheet 5 iswider and extends to seals 1 and 2. Under some circumstances, this andthe other embodiments, below, which utilize a wider sheet 5 may beeasier to manufacture. However, the method and the product which utilizethe smaller width sheet 5 are generally preferred as there is amaterials savings with a shorter width sheet 5. FIGS. 16, 17, and 18 aresimilar to FIGS. 11, 13, and 14, respectively, except that sheet 5extends to seals 1 and 2.

FIGS. 3 and 3A show alternate embodiments of the present invention, amulti-use hot or cold chemical pack 30. Generally, the FIG. 3 embodimentis preferred as it is believed easier to manufacture. Similar to theFIGS. 1 and 2 embodiment, this multi-use pack 30 includes a "first-use"pack 41 which includes a first compartment 11, a second compartment 12,a third compartment 13, a first breakable wall 5A and second breakablewall 5B, where the breakable walls 5A, 5B and compartment 13 separatethe first compartment 11 and the second compartment 12. A "second-use"pack 42, represented by fourth compartment 31, fifth compartment 32,sixth compartment 33, third breakable wall 35A, and fourth breakablewall 35B operates in a similar fashion as discussed above.

For multi-use chemical packs 30 which use a liquid substance to becombined with a solid substance, it is preferred that the second-usepack 42 be a reverse mirror image of the first use pack 41. Thus, if theliquid substance is contained in compartment 11 of the first-use pack41, then the liquid substance would be contained in fifth compartment 32of the second-use pack 42, such that a compartment containing a liquidis in proximity with a compartment containing a solid substance on eachside of the multi-use pack 30. This reverse mirror image orientation ispreferred as liquids transfer hydraulic force and solids do not. This ispreferred because, if the first-use pack 41 is desired to be activated,the user applies a force, e.g., by squeezing, the liquid containingcompartment to force the liquid to rupture the breakable walls. Sincethe solid material on the same side of the multi-use pack 30 which isreceiving the same force does not transfer the force, only the first-usepack 41 activates and the second-use pack 42 does not activate until aforce is applied to its liquid containing compartment.

An important advantage of the multi-use pack 30 is that it can be usedmore than once, which makes the pack more convenient to use and lesscostly for the user. Also, one multi-use pack 30 could be used both as ahot and cold pack, which increases the versatility of the pack whilereducing its cost to the user.

With the embodiment of FIG. 3, it is preferred that sheet 38 be of athicker or a more impermeable plastic to prevent the migration of asubstance across sheet 38 into the substance on the other side of sheet38, such that the multi-use pack 30 maintains a long shelf life and highefficiency upon activation. Sheet 38 may also be made from a materialthat has hot or cold insulating properties, such as, for example, alayer of foam material. Sheet 38 may be constructed of an insulatingmaterial when it is desired that the heat or cold generated by multi-usepack 30 be directed substantially toward the exterior surface 36 for thefirst-use pack 41 and exterior surface 37 for the second-use pack 42, soas to increase efficiency upon use.

FIGS. 4 and 5 show an alternate embodiment of the FIGS. 1 and 2 device(like numerals used for corresponding parts) which includes a firstelongated strip 51 and a second elongated strip 52 which together serveas ties such that a user may fasten a multi-compartment bag or amulti-use chemical pack to a particular part of his body. The first andsecond elongated strips 51, 52 may be fastened to the bag 50 in anysuitable way. Preferably, strips 51, 52 are sealed to perimeter seals,i.e., seals 1, 2, 9, and 10. While strips 51, 52 are shown sealed toseals 9 and 10, alternatively, the strips 51 and 52 could be sealed toseals 1 and 2. Most preferably, the strips 51 and 52 are folded over twoperimeter seals, shown here as seals 9 and 10, then sealed to theexisting seal, such that at the portion of the strip 51, 52 which issealed to the bag 50, there exist four layers of materials, i.e., sheets3 and 4 and two folded sections of the strips 51, 52. If folded, it ispreferred that the strips 51, 52 be folded along their entire length, asthis provides a stronger tie.

Thus, it can be seen that the first elongated strip 51 has a centersection 55 which is sealed to seal 9 and two ends 53 which extendlongitudinally from seal 9. Likewise, the second elongated strip 52 hasa center section 56 which is sealed to seal 10 and has two ends 54 whichextend longitudinally from seal 10.

This method of attaching strips 51, 52 as ties is preferred as it doesnot cause stresses which would tend to tear the bag 50 and releasechemicals upon the user. The strips 51, 52 are preferably installedafter the bag 50 has been assembled, including filled with the desiredsubstances. As such, care should be taken such that when the strips 51and 52 are fastened or sealed to the bag 50 they do not extend into thefirst compartment 11 or second compartment 12 so as to weaken thesecompartments or cause exterior leaking of the chemical.

For hot or cold packs where it is desired to mix two substances toachieve the endothermic or exothermic reaction, the third compartment 13may be essentially empty or it may contain an inert substance such asair or inert gas which may allow the breakable walls 5A, 5B to breakeasier due to the compressive nature of the gas. In liquid/liquidsystems, having some air or inert gas may be advantageous because, in asituation such as a bag-in-bag design where liquid is on both sides ofthe wall to be ruptured, it can be difficult to rupture the wall. Also,in liquid/liquid systems, a certain amount of gas, such as air ornitrogen is helpful in allowing for the quick mixing of the two liquids.

The bags 20 and multi-use packs 30 may be used without a cover or mayinclude a non-woven soft exterior cover 16 (FIG. 1A) which substantiallysurrounds the bag, such as paper or other materials to increase theuser's comfort.

The bags 20 and multi-use packs 30 of the present invention, may beformed in any size or shape to meet their intended purpose or fit anintended body area and it is not intended that the figures shown hereinare limiting in any way as to the shapes which are covered by thispatent. For each design, the two substances which are to be mixed shouldbe separated by two walls, at least a portion of which are breakablewalls, and a third compartment which may be substantially empty orcontain air or an inert substance.

Sheets 3, 4, and 5 may be of any suitable material. Preferably sheets 3,4, and 5 are of a relatively flexible, plastic or vinyl sheet material,e.g., polyethylene, polypropylene, polyvinylchloride, mylar, cellophaneor vinyl. Generally, any flexible sheet material may be used as long asit is capable of being effectively sealed as discussed herein.Generally, breakable sheet 5, if made of the same plastic as sheets 3and 4, is thinner than sheets 3 and 4 such that breakable sheet 5 wouldrupture before sheets 3 and 4. Breakable sheet 5 may alternatively bemade of a different, weaker plastic than sheets 3 and 4 such thatbreakable sheet 5 will rupture before sheets 3 and 4.

Seals 1, 2, 6, 7, 8, 9, and 10 are preferably strong heat seals.However, any suitable method of sealing these sheets at the desiredlocation may be used, such as, for example, an RF seal, ultrasonicseals, glue, etc.

The multi-compartment bags 20 and multi-use packs 30 may be manufacturedin a variety of configurations. For example, breakable sheet 5 could besubstituted for by two separate sheets, each sheet forming a breakablewall. Also, the breakable walls 5A, 5B could be just a portion of alarger wall.

The multi-compartment bags 20 and the multi-use packs 30 solve theproblems mentioned above by providing a chemical pack which has a longshelf life, high efficiency upon activation, high reliability, and easeof use. These advantages are due to the inventive concept of providing athird compartment 13 between the two compartments 11 and 12 containingthe two substances to be mixed. The third compartment 13 is essentiallyempty or contains an inert substance and its perimeter includes twobreakable walls 5A, 5B which allow intermixing of the two substances.

Although the present inventions and its advantages have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made therein without departing from the spiritand scope of the invention as defined by the appended claims.

What is claimed is:
 1. A multi-use hot or cold chemical pack,comprising:a first compartment for holding a first substance having afirst breakable wall; a second compartment for holding a secondsubstance having a second breakable wall; a third compartment interposedbetween the first compartment and the second compartment having aperimeter including the first breakable wall and the second breakablewall; a fourth compartment for holding a third substance having a thirdbreakable wall; a fifth compartment for holding a fourth substancehaving a fourth breakable wall; and a sixth compartment interposedbetween the fourth compartment and the fifth compartment having aperimeter including the third breakable wall and the fourth breakablewall; wherein the first compartment is proximal to the fourthcompartment and the second compartment is proximal to the fifthcompartment.
 2. The multi-use pack of claim 1, wherein when a firstsufficient force is exerted upon the pack, the first breakable wall andthe second breakable wall rupture, causing mixing of the first substanceand the second substance.
 3. The multi-use pack of claim 2, wherein whena second sufficient force is exerted upon the pack, the third breakablewall and the fourth breakable wall rupture, causing mixing of the thirdsubstance and the fourth substance.
 4. The multi-use pack of claim 1wherein the third compartment acts as a barrier between the firstcompartment and the second compartment to minimize pre-activationintermixing of the first substance and the second substance.
 5. Themulti-use pack of claim 1, wherein the sixth compartment acts as abarrier between the fourth compartment and the fifth compartment tominimize pre-activation intermixing of the third substance and thefourth substance.
 6. The multi-use pack of claim 1, wherein the secondand third substances comprise a solid substance.
 7. The multi-use packof claim 6, wherein the second and third substances comprise a pluralityof prills.
 8. The multi-use pack of claim 1, further comprising twostrips fastened to the pack to serve as ties.
 9. A multi-use hot or coldchemical pack, comprising:a first sheet, a second sheet and a thirdsheet, wherein the first sheet, the second sheet and the third sheet aresealed together to form a first internal compartment and a secondinternal compartment; a first breakable wall, a second breakable wall, athird breakable wall and a fourth breakable wall; wherein the firstbreakable wall and the second breakable wall are arranged in the firstinternal compartment and are sealed to the first sheet and the secondsheet so as to form a first compartment for holding a first substance, asecond compartment for holding a second substance, and a thirdcompartment interposed between the first and the second compartment;wherein the third breakable wall and the fourth breakable wall arearranged in the second internal compartment and are sealed to the secondsheet and the third sheet so as to form a fourth compartment for holdinga third substance, a fifth compartment for holding a fourth substance,and a sixth compartment interposed between the fourth compartment andthe fifth compartment; wherein the first compartment is proximal to thefourth compartment and the second compartment is proximal to the fifthcompartment.
 10. The multi-use pack of claim 9, wherein when a firstsufficient force is exerted upon the pack, the first breakable wall andthe second breakable wall rupture, causing mixing of the first substanceand the second substance.
 11. The multi-use pack of claim 10, whereinwhen a second sufficient force is exerted upon the pack, the thirdbreakable wall and the fourth breakable wall rupture, causing mixing ofthe third substance and the fourth substance.
 12. The multi-use pack ofclaim 9, wherein the third compartment acts as a barrier between thefirst compartment and the second compartment to minimize pre-activationintermixing of the first substance and the second substance.
 13. Themulti-use pack of claim 9, wherein the sixth compartment acts as abarrier between the fourth compartment and the fifth compartment tominimize pre-activation intermixing of the third substance and thefourth substance.
 14. The multi-use pack of claim 9, wherein the secondand third substances comprise a solid substance.
 15. The multi-use packof claim 14, wherein the second and third substances comprise aplurality of prills.
 16. The multi-use pack of claim 9, furthercomprising two strips fastened to the pack to serve as ties.